Despite preponderant power, unipoles often do not get their way. Why? Scholars interested in polarity and the systemic structures determined by the distribution of power have largely focused on material power alone, but the structure of world politics is as much social as it is material. In this article the author explores three social mechanisms that limit unipolar power and shape its possible uses. The first involves legitimation. To exercise power effectively, unipoles must legitimate it and in the act of legitimating their power, it must be diffused since legitimation lies in the hands of others. The second involves institutionalization. A common way to legitimate power is to institutionalize it. Institutionalizing power in rational-legal authorities fundamentally transforms it, however. Once in place, institutions, laws, and rules have powers and internal logics of their own that unipoles find difficult to control. The third relates to hypocrisy. The social structures of legitimation and insti tutionalization do more than simply diffuse power away from the unipole; they create incentives for hypocrisy. Hypocrisy is a double-edged sword for unipoles. On the one hand, unrestrained hypocrisy by unipoles undermines the legitimacy of their power. On the other hand, judicious hypocrisy can provide crucial strategies for melding ideals and interests. Indeed, honoring social ideals or principles in the breach can have long-lasting political effects, as decades of U.S. hypocrisy about democratization and human rights suggest.